Mehta R G, Cerny W L, Moon R C
Biochem J. 1982 Dec 15;208(3):731-6. doi: 10.1042/bj2080731.
Cellular retinoic acid-binding protein (CRABP) was detected in the nuclear fraction of N-methyl-N-nitrosourea-induced mammary cancers after the incubation of cytosol containing [3H]retinoic acid (RA)-bound CRABP with isolated nuclei. CRABP extracted from the nuclei in buffer containing 0.4 M-KCl sedimented as a 2 S component when subjected to sucrose-density-gradient analysis. [3H]RA-CRABP was found to be a prerequisite for the detection of nuclear binding, since the incubation of isolated nuclei or 0.4 M-KCl extract of the nuclei with [3H]RA did not result in any significant binding. Incubation of [3H]RA-CRABP at 25 or 30 degrees C before incubation with the nuclei neither altered the sedimentation coefficient nor enhanced the nuclear binding compared with 0 degrees C incubation. The tumour nuclei contained a saturable number of binding sites with a dissociation constant of 1.6 x 10(-9) M. These results indicate that the action of retinoic acid in the target organ may be mediated by its interaction with the nuclei.
在用含有与[3H]视黄酸（RA）结合的细胞视黄酸结合蛋白（CRABP）的胞质溶胶与分离的细胞核孵育后，在N-甲基-N-亚硝基脲诱导的乳腺癌的核部分中检测到了CRABP。当在含0.4 M-KCl的缓冲液中从细胞核中提取的CRABP进行蔗糖密度梯度分析时，它以2 S成分沉降。发现[3H]RA-CRABP是检测核结合的先决条件，因为将分离的细胞核或细胞核的0.4 M-KCl提取物与[3H]RA孵育不会导致任何明显的结合。与在0℃孵育相比，在与细胞核孵育前于25或30℃孵育[3H]RA-CRABP既不会改变沉降系数也不会增强核结合。肿瘤细胞核含有饱和数量的结合位点，解离常数为1.6×10^(-9) M。这些结果表明视黄酸在靶器官中的作用可能是通过其与细胞核的相互作用介导的。
